KR102338712B1 - Active touch pen and touch sensing system and driving method of the same - Google Patents

Abstract

The touch sensing system according to the present invention includes a touch screen, a touch driving device for applying a touch driving signal to the touch screen and sensing a change in capacitance of the touch screen to calculate a plurality of touch input coordinates, and a pen driving signal synchronized with the touch driving signal and an active touch pen that transmits through the tip and senses the pressure applied in the vertical direction of the tip when the tip contacts the touch screen to generate pressure information and provides the pressure information to the touch driving device. The touch driving device includes a touch input calculator, a horizontal angle calculator, an error length calculator, and a touch input corrector. The touch input calculator calculates pen touch coordinates and palm peak coordinates according to the number of labels in the plurality of touch input coordinates. The horizontal angle calculator calculates the palm peak coordinate direction in the pen touch coordinates as a tip horizontal vector, and calculates horizontal angle information between the reference axis and the tip horizontal vector in the touch coordinate system. The error length calculator calculates the error length of the pen touch coordinates based on the pressure information. The touch input correction unit calculates touch correction coordinates obtained by compensating for an error length in the negative vector direction opposite to the tip horizontal vector from the pen touch coordinates.

Description

ACTIVE TOUCH PEN AND TOUCH SENSING SYSTEM AND DRIVING METHOD OF THE SAME

The present invention relates to a touch sensing system, and more particularly, to a touch sensing system capable of performing a touch input through an active touch pen and a driving method thereof.

A user interface (UI) enables a person (user) to easily control various electronic devices as desired. Representative examples of such a user interface include a keypad, a keyboard, a mouse, an on-screen display (OSD), a remote controller having an infrared communication function or a radio frequency (RF) communication function. User interface technology is developing in the direction of increasing user sensitivity and ease of operation. Recently, a user interface is evolving into a touch UI, a voice recognition UI, a 3D UI, and the like.

Touch UI is essential for portable information devices. The touch UI is implemented as a method of forming a touch screen on the screen of a display device. Such a touch screen may be implemented in a capacitive manner. A touch screen having a capacitive touch sensor senses a change in capacitance according to an input of a touch screen driving signal, that is, a change in charge of the touch sensor, when a finger or a conductive material is in contact with (or close to) the touch sensor. to detect a touch input.

The capacitive touch sensor may be implemented as a self-capacitance sensor or a mutual capacitance sensor. Each of the electrodes of the self-capacitance sensor may be 1:1 connected to sensor wires formed along one direction. The mutual capacitive sensor may be formed at the intersection of the orthogonal sensor wirings with a dielectric layer interposed therebetween.

Recently, not only a finger but also a touch pen (Stylus Pen) is widely used as a Human Interface Device (HID) in smart phones and smart books. There are two types of touch pens: passive and active. The passive type has little change in capacitance at the point of contact with the touch screen, making it difficult to detect the touch position. The active type generates a pen driving signal by itself and outputs it at the point of contact with the touch screen, so it is easier to detect the touch position compared to the passive type.

Since the touch pen has the advantage of being able to input more precisely than a finger, a touch input is essential even in a small touch screen device, and it can also perform a writing function. However, since the precision of the touch pen is significantly lower than that of an analog writing tool, the precision of the touch pen is still insufficient to satisfy the needs of users.

Accordingly, an object of the present invention is to provide a touch pen capable of performing a more precise touch input with the touch pen, a touch sensing system including the same, and a driving method thereof.

In order to achieve the above object, the touch sensing system according to the present invention is a touch screen, a touch driving device for applying a touch driving signal to the touch screen and sensing a change in capacitance of the touch screen to calculate a plurality of touch input coordinates, and a touch driving device An active touch pen that transmits a pen driving signal synchronized with the signal through the tip and senses the pressure applied in the vertical direction of the tip when the tip contacts the touch screen to generate pressure information and provide the pressure information to the touch driving device includes The touch driving device includes a touch input calculator, a horizontal angle calculator, an error length calculator, and a touch input corrector. The touch input calculator calculates pen touch coordinates and palm peak coordinates according to the number of labels in the plurality of touch input coordinates. The horizontal angle calculator calculates the palm peak coordinate direction in the pen touch coordinates as a tip horizontal vector, and calculates horizontal angle information between the reference axis and the tip horizontal vector in the touch coordinate system. The error length calculator calculates the error length of the pen touch coordinates based on the pressure information. The touch input correction unit calculates touch correction coordinates obtained by compensating for an error length in the negative vector direction opposite to the tip horizontal vector from the pen touch coordinates.

The present invention calculates an error length at which the tip is tilted based on vertical information applied to the tip, calculates a horizontal angle in the direction the pen faces based on the area the user's hand touches, and touches using the error length and horizontal angle Correct the input coordinates. Accordingly, it is possible to more accurately calculate the point where the actual user touches the tip.

1 is a diagram schematically showing a touch sensing system of the present invention.
2 is a view showing a display device to which a touch sensing system according to an embodiment of the present invention is applied;
3 is a view showing an example of a touch screen implemented as a mutual capacitive sensor.
4 is a view showing an example of a touch screen implemented as a magnetocapacitive sensor;
5 to 7 are views showing a touch driving device according to an embodiment of the present invention.
8 is a view showing that one frame is time-divided into a display driving period and a touch sensor driving period;
9 to 12 are views showing the configuration of an active touch pen according to the present invention.
13 is a diagram illustrating a touch screen driving signal and a touch pen driving signal;
14 is a flowchart illustrating an operation of a touch compensator;
15 and 16 are diagrams illustrating calculation of touch input coordinates and palm coordinates;
17 is a schematic diagram showing a touch input correction method;

Hereinafter, with reference to the accompanying drawings, a preferred embodiment of the present invention will be described. Like reference numerals refer to substantially identical elements throughout. In the following description, if it is determined that a detailed description of a known technology or configuration related to the present invention may unnecessarily obscure the subject matter of the present invention, the detailed description thereof will be omitted. In addition, the component names used in the following description may be selected in consideration of ease of writing the specification, and may be different from the component names of the actual product.

1 schematically shows a touch sensing system of the present invention.

Referring to FIG. 1 , the touch sensing system of the present invention includes a display device 10 and an active touch pen 20 .

The display device 10 performs a display function and a touch detection function. The display device 10 is capable of detecting a touch by contact with a conductive object such as a finger or an active touch pen 20 , and has a capacitive touch screen integrally formed therein. Here, the touch screen may be configured in a form independent of a display panel for display implementation, or may be built in a pixel array of the display panel. A detailed configuration and operation of the display device 10 will be described later with reference to FIGS. 2 to 8 .

The active touch pen 20 generates a pen drive signal based on a touch screen drive signal received from the touch screen and outputs it to a point of contact with the touch screen, thereby facilitating detection of a touch position on the touch screen. The active touch pen 20 acquires vertical pressure information and pen pressure information when the tip contacts the touch screen. The vertical pressure information is used in the process of correcting the touch input coordinates. The pen pressure information is used to modulate the pen driving signal.

2 shows a display device to which a touch sensing system according to an embodiment of the present invention is applied. 3 shows an example of a touch screen implemented as a mutual capacitive sensor. 4 shows an example of a touch screen implemented as a magnetic capacitive sensor. 5 to 7 show a touch driving device according to an embodiment of the present invention.

2 to 7 , the display device 10 of the present invention includes a liquid crystal display (LCD), a field emission display (FED), and a plasma display panel (PDP). ), an organic light emitting diode display (OLED), an electrophoresis display device (EPD), etc. can be implemented based on a flat panel display device. In the following embodiments, it will be described that the display device is implemented as a liquid crystal display device, but the display device of the present invention is not limited to the liquid crystal display device.

The display device 10 includes a display module and a touch module.

The touch module includes a touch screen (TSP) and a touch driving device 18 .

The touch screen TSP may be implemented in a capacitive manner that senses a touch input through a plurality of capacitive sensors. The touch screen TSP includes a plurality of touch sensors having capacitance. The capacitance may be divided into self capacitance and mutual capacitance. Self-capacitance may be formed along a single-layered conductor wiring formed in one direction, and mutual capacitance may be formed between two orthogonal conductor wirings.

The touch screen TSP implemented as the mutual capacitive sensor Cm, as shown in FIG. 3 , includes Tx electrode lines, Rx electrode lines crossing the Tx electrode lines, and the intersections of the Tx electrode lines and the Rx electrode lines. It may include formed touch sensors Cm. The Tx electrode lines are driving signal wires for supplying electric charges to the touch sensors by applying a touch screen driving signal to each of the touch sensors Cm. The Rx electrode lines are sensor wires connected to the touch sensors Cm to supply electric charges of the touch sensors to the touch driving device 18 . In the mutual capacitance sensing method, a driving signal is applied to the Tx electrode through the Tx electrode line to supply electric charge to the touch sensor (Cm), and the touch sensor (Cm) is synchronized with the touch screen driving signal through the Rx electrode and the Rx electrode line. A touch input can be recognized by sensing a change in capacitance.

The touch screen TSP implemented as the self-capacitance sensor Cs may be 1:1 connected to the sensor wires 32 in which each of the touch electrodes 31 are formed along one direction as shown in FIG. 4 . The self-capacitance sensor Cs includes a capacitance formed in each of the electrodes 31 . In the self-capacitance sensing method, when a touch screen driving signal is applied to the electrode 31 through the sensor wiring 32 , electric charges Q are accumulated in the touch sensor Cs. At this time, when a finger or a conductive object comes into contact with the electrode 31 , an additional parasitic capacitance Cf is connected to the self-capacitance sensor Cs, and the total capacitance value changes. Accordingly, a capacitance value is different between a sensor touched by a finger and a sensor not touched by the finger, so that it can be determined whether a touch is made.

The touch screen TSP may be bonded to the upper polarizing plate of the display panel DIS or formed between the upper polarizing plate and the upper substrate of the display panel DIS. Also, the touch sensors Cm or Cs of the touch screen TSP may be embedded in the pixel array of the display panel DIS.

The touch driving device 18 senses the amount of charge change of the touch sensor before and after the touch, and determines whether a conductive material such as a finger (or a touch pen) is touched and its location.

The touch driving device 18 of the present invention may be implemented as an IC (Integrate Circuit) package of the form shown in FIGS. 5 to 7 .

Referring to FIG. 5 , the touch driving device 18 includes a driver IC (DIC) and a touch IC (TIC).

The driver IC (DIC) includes a touch sensor channel unit 100, a Vcom buffer 110, a switch array 120, a timing control signal generator 130, a multiplexer (MUX) 140, and a DTX compensator ( 150).

The touch sensor channel unit 100 is connected to the electrodes of the touch sensors through sensor wires (or Rx electrode lines), and is connected to the Vcom buffer 110 and the multiplexer 140 through the switch array 120 . The multiplexer 140 connects the sensor wires to the touch IC (TIC). In the case of the 1:3 multiplexer, the multiplexer 140 reduces the number of channels of the touch IC (TIC) by sequentially connecting one channel of the touch IC (TIC) to three sensor wires according to a time division method. The multiplexer 140 sequentially selects sensor wires to be connected to a channel of the touch IC TIC in response to the MUX control signals MUX C1 to C3. The multiplexer 140 is connected to channels of the touch IC (TIC) through touch lines.

The Vcom buffer 110 outputs the common voltage Vcom of the pixel. The switch array 120 supplies the common voltage Vcom from the Vcom buffer 110 to the touch sensor channel unit 100 during the display driving period under the control of the timing control signal generator 130 . The switch array 120 connects the sensor wires to the touch IC (TIC) during the touch sensor driving period under the control of the timing control signal generator 130 .

The timing control signal generator 130 generates timing control signals for controlling operation timings of the display driving circuit and the touch IC (TIC). The display driving circuit includes a data driving circuit 12 and a gate driving circuit 14 for writing input image data to pixels. The data driving circuit 12 generates a data voltage and supplies it to the data lines D1 to Dm of the display panel DIS. The data driving circuit 12 may be integrated in a driver IC (DIC). The gate driving circuit 14 sequentially supplies a gate pulse (or scan pulse) synchronized with the data voltage to the gate lines GL1 to GLn of the display panel DIS. The gate driving circuit 14 may be disposed together with the pixels on the substrate of the display panel DIS.

The timing control signal generator 130 is substantially the same as the timing control signal generator in the timing controller 16 shown in FIG. 2 . The timing control signal generator 130 drives the display driving circuit during the display driving period and drives the touch IC (TIC) during the touch sensor driving period.

The timing control signal generator 130 generates a touch enable signal TEN defining the display driving period T1 and the touch sensor driving period T2 as shown in FIG. 8 to connect the display driving circuit and the touch IC (TIC). synchronize The display driving circuit writes data to the pixels during the first level period of the touch enable signal TEN. The touch IC (TIC) senses a touch input by driving touch sensors in response to the second level of the touch enable signal (TEN). The first level of the touch enable signal TEN may be a low level and the second level may be a high level, but vice versa.

The touch IC (TIC) is connected to a driving power supply (not shown) to receive driving power. The touch IC TIC generates a touch screen driving signal in response to the second level of the touch enable signal TEN and applies it to the touch sensors of the touch screen TSP. The touch screen driving signal may be generated in various forms such as a square wave pulse, a sine wave, or a triangular wave, but is preferably implemented as a square wave. The touch screen driving signal may be applied N times to each of the touch sensors so that charges may be accumulated in the integrator of the touch IC (TIC) N (N is a natural number equal to or greater than 2) times or more.

Noise may increase in the touch sensor signal according to a change in input image data. The DTX compensator 150 analyzes the input image data, removes the noise component from the touch raw data according to the grayscale change of the input image, and transmits it to the touch IC (TIC). DTX stands for Display and Touch crosstalk. The content related to the DTX compensation unit 150 is described in detail in Patent Application No. 10-2012-0149028 (filed on December 19, 2012) previously filed by the applicant of the present application. In the case of a system in which the noise of the touch sensor does not change sensitively according to the data change of the input image, the DTX compensator 150 is not required and thus may be omitted. In FIG. 5 , DTX DATA is output data of the DTX compensator 150 .

The touch IC (TIC) drives the multiplexer 140 during the touch sensor driving period T2 in response to the touch enable signal TEN from the timing control signal generator 130 through the multiplexer 140 and the sensor wires. Receive the charge of the touch sensor. In FIG. 5, MUXs C1 to C3 are signals for selecting channels of the multiplexer.

The touch IC (TIC) detects a charge change amount before and after a touch input from a touch sensor signal, compares the phone change amount with a predetermined threshold value, and determines positions of touch sensors having a charge change amount greater than or equal to the threshold value as the touch input area. The touch IC (TIC) transmits touch data TDATA(XY) including touch input coordinate information to an external host system by calculating coordinates for each touch input. A touch IC (TIC) includes an amplifier that amplifies the charge of the touch sensor, an integrator that accumulates the charge received from the touch sensor, an analog to digital converter (ADC) that converts the voltage of the integrator into digital data, and an arithmetic logic unit. The operation logic unit compares the touch raw data output from the ADC with a threshold value, determines a touch input according to the comparison result, and executes a touch recognition algorithm that calculates coordinates.

The driver IC (DIC) and the touch IC (TIC) may transmit and receive signals through a Serial Peripheral Interface (SPI) interface.

The host system 19 refers to a system body of an electronic device to which the display device 10 of the present invention is applicable. The host system 19 may be any one of a phone system, a TV (Television) system, a set-top box, a navigation system, a DVD player, a Blu-ray player, a personal computer (PC), and a home theater system. The host system 19 transmits input image data (RGB) to the driver IC (DIC) and receives the touch input data (TDATA(XY)) from the touch IC (TIC) to generate an application related to the touch input. run

Referring to FIG. 6 , the touch driving device 18 includes a driver IC (DIC) and a micro controller unit (MCU).

The driver IC (DIC) includes a touch sensor channel unit 100 , a Vcom buffer 110 , a switch array 120 , a first timing control signal generating unit 130 , a multiplexer 140 , a DTX compensator 150 , and sensing. It includes a unit 160 , a second timing control signal generating unit 170 , and a memory 175 . This embodiment is different from the above-described embodiment of FIG. 5 in that the sensing unit 160 and the second timing control generating unit 170 are integrated in the driver IC (DIC). The first timing control generator 130 is substantially the same as that of FIG. 5 . Accordingly, the first timing control generator 130 generates timing control signals for controlling operation timings of the display driving circuit and the touch IC (TIC).

The sensing unit 160 includes an amplifier for amplifying the charge of the touch sensor, an integrator for accumulating the charge received from the touch sensor, and an ADC for converting the voltage of the integrator into digital data. Touch raw data (TDATA) output from ADC is transmitted to MCU. The second timing control generating unit 170 generates a timing control signal, a clock, and the like for controlling the operation timing of the multiplexer 140 and the sensing unit 160 . The DTX compensator 150 in the driver IC (DIC) may be omitted. The memory 180 temporarily stores the touch raw data TDATA under the control of the second timing control generator 170 .

The driver IC (DIC) and the MCU may transmit and receive signals through an SPI (Serial Peripheral Interface) interface. The MCU executes a touch recognition algorithm that compares the raw touch data (TDATA) with a threshold value, determines a touch input according to the comparison result, and calculates coordinates.

Referring to FIG. 7 , the touch driving device 18 includes a driver IC (DIC) and a memory (Memory, MEM).

The driver IC (DIC) includes a touch sensor channel unit 100 , a Vcom buffer 110 , a switch array 120 , a first timing control signal generating unit 130 , a multiplexer 140 , a DTX compensator 150 , and sensing. It includes a unit 160 , a second timing control signal generating unit 170 , a memory 175 , and an MCU 190 . This embodiment is different from the embodiment of FIG. 6 described above in that the MCU 190 is integrated in the driver IC (DIC). The MCU 190 compares the raw touch data TDATA temporarily stored in the memory 175 with a threshold value, and determines a touch input according to the comparison result and executes a touch recognition algorithm for calculating coordinates.

The memory 175 stores a register setting value related to timing information required for the operation of the display driving circuit and the sensing unit 160 . The register setting value is loaded from the memory MEM to the first timing control signal generator 16 and the second timing control signal generator 170 when the power of the display device is turned on. The first timing control signal generating unit 16 and the second timing control signal generating unit 170 generate timing control signals for controlling the display driving circuit and the sensing unit 160 based on the register setting value read from the memory. do. It is possible to respond to the model change by changing the register setting value of the memory (MEM) without structural change of the driving device.

The display module may include a display panel DIS, display driving circuits 12 , 14 , and 16 , and a host system 19 .

The display panel DIS includes a liquid crystal layer formed between two substrates. The pixel array of the display panel DIS includes pixels formed in a pixel area defined by data lines D1 to Dm, m is a positive integer) and gate lines G1 to Gn, n is a positive integer. . Each of the pixels is connected to TFTs (Thin Film Transistor) formed at intersections of the data lines D1 to Dm and the gate lines G1 to Gn, a pixel electrode charging the data voltage, and the pixel electrode of the liquid crystal cell. It may include a storage capacitor (Cst) for maintaining the voltage, and the like.

A black matrix, a color filter, etc. may be formed on the upper substrate of the display panel DIS. The lower substrate of the display panel DIS may be implemented in a color filter on TFT (COT) structure. In this case, the black matrix and the color filter may be formed on the lower substrate of the display panel DIS. The common electrode to which the common voltage is supplied may be formed on an upper substrate or a lower substrate of the display panel DIS. A polarizing plate is attached to each of the upper and lower substrates of the display panel DIS, and an alignment layer for setting a pretilt angle of the liquid crystal is formed on the inner surface in contact with the liquid crystal. A column spacer for maintaining a cell gap of the liquid crystal cell is formed between the upper substrate and the lower substrate of the display panel DIS.

A backlight unit may be disposed under the rear surface of the display panel DIS. The backlight unit is implemented as an edge type or direct type backlight unit to irradiate light to the display panel DIS. The display panel DIS may be implemented in any known liquid crystal mode, such as a twisted nematic (TN) mode, a vertical alignment (VA) mode, an in plane switching (IPS) mode, or a fringe field switching (FFS) mode.

The display driving circuit includes a data driving circuit 12 , a gate driving circuit 14 , and a timing controller 16 to write video data of an input image to pixels of the display panel DIS. The data driving circuit 12 converts digital video data RGB input from the timing controller 16 into analog positive/negative gamma compensation voltages and outputs a data voltage. The data voltage output from the data driving circuit 12 is supplied to the data lines D1 to Dm. The gate driving circuit 14 sequentially supplies a gate pulse (or scan pulse) synchronized with the data voltage to the gate lines G1 to Gn to select a pixel line of the display panel DIS to which the data voltage is written.

The timing controller 16 inputs timing signals such as a vertical synchronization signal Vsync, a horizontal synchronization signal Hsync, a data enable signal DE, and a main clock MCLK input from the host system 19 . In response, the operation timings of the data driving circuit 12 and the gate driving circuit 14 are synchronized. The scan timing control signal includes a gate start pulse (GSP), a gate shift clock (Gate Shift Clock), a gate output enable signal (Gate Output Enable, GOE), and the like. The data timing control signal includes a source sampling clock (Source Sampling Clock, SSC), a polarity control signal (Polarity, POL), and a source output enable signal (Source Output Enable, SOE).

The host system 19 transmits the timing signals Vsync, Hsync, DE, MCLK together with the digital video data RGB to the timing controller 16 , and touch coordinate information XY input from the touch driving device 18 . ) and related applications can be executed.

Meanwhile, the touch enable signal TEN may be generated by the host system 19 . During the display driving period T1 , the data driving circuit 12 supplies a data voltage to the data lines D1 to Dm under the control of the timing controller 16 , and the gate driving circuit 14 operates the timing controller 16 . A gate pulse synchronized with the data voltage is sequentially supplied to the gate lines G1 to Gn under the control of . Meanwhile, during the display driving period T1, the touch driving device 18 stops operating.

During the touch sensor driving period T2 , the touch driving device 18 applies a touch screen driving signal to the touch sensors of the touch screen TSP. Meanwhile, during the touch sensor driving period T2, the display driving circuits 12, 14, and 16 are configured to minimize parasitic capacitance between the signal lines D1 to Dm and G1 to Gn connected to the pixels and the touch sensors. An AC signal having the same amplitude and the same phase as the touch screen driving signal may be supplied to the signal lines D1 to Dm and G1 to Gn. In this case, the display noise mixed into the touch sensing signal is remarkably reduced, and thus the accuracy of the touch sensing is increased.

9 and 10 are perspective views of the active touch pen according to the present invention, and FIGS. 11 and 12 are views showing the internal configuration of the active touch pen.

Referring to FIGS. 9 to 12 , the active touch pen of the present invention is as follows. The active touch pen 20 includes a housing 280 and a tip 210 protruding from one end of the housing 280 . Inside the housing 280 , a vertical pressure sensing unit 216 is disposed around the tip 210 , and a switching unit 220 is disposed at an end of the tip 210 . And inside the housing, the receiving unit 230 for receiving the touch screen driving signal input from the tip 210 through the switching unit 220, based on the touch screen driving signal from the receiving unit 230 is synchronized thereto, the pressure information A signal processing unit 250 for generating a modulated pen driving signal including, and a driving unit 240 for supplying the modulated pen driving signal generated by the signal processing unit 250 to the tip 210 through the switching unit 220 after level-shifting and a power supply unit 260 for generating driving power required for operation, and an input/output interface 270 .

The tip 210 is made of a conductive material such as metal, and serves as a receiving electrode and a transmitting electrode. When the tip 210 makes contact on the touch screen TSP of the display device, the tip 210 is coupled to the touch screen TSP at the contact point. The tip 210 receives the touch screen driving signal from the touch screen TSP at the contact point, and then transmits the modulated pen driving signal generated inside the active touch pen 20 to the touch screen TSP to be synchronized with the touch screen TSP. send to the branch.

The vertical pressure sensing unit 216 of the tip 210 senses the pressure F1 applied perpendicularly to the longitudinal direction of the tip 210 when the tip 210 comes into contact with the touch screen TSP.

The pen pressure sensing unit 217 senses the pressure F2 applied in the longitudinal direction of the tip 210 .

When the tip 210 is in contact with the touch screen TSP of the display device 20 , the switching unit 220 electrically connects the tip 210 and the receiving unit 230 for a first time. , by electrically connecting the tip 210 and the driving unit 240 for the second time, the reception timing of the touch screen driving signal and the transmission timing of the modulated pen driving signal are temporally separated. Since the tip 210 serves as both a receiving electrode and a transmitting electrode, there is an advantage in that the structure of the active touch pen 20 is simplified.

The receiver 230 may include at least one amplifier to amplify the touch screen driving signal input from the tip 210 through the switching unit 220 . The receiving unit 230 compares the amplified signal including the comparator with a preset reference voltage, and outputs the result to the signal processing unit 250 .

The signal processing unit 250 analyzes the comparator output signal input from the receiving unit 230 for one frame or more to generate a pen driving signal synchronized with the touch screen driving signal, and then a pressure sensing unit (not shown) connected to the tip 210 . The pen driving signal is modulated based on the pressure information input from the , and then the modulated pen driving signal is output to the driving unit 240 .

The driving unit 240 includes a level shifter 243 to shift the voltage level of the modulated pen driving signal. The driving unit 240 outputs the level-shifted modulated pen driving signal to the tip 210 through the switching unit 220 .

The input/output interface 270 may be connected to the power supply unit 260 according to a user's button press operation to supply necessary power to the receiving unit 230 , the driving unit 240 , and the signal processing unit 250 .

Referring to FIG. 12 , the operation of the pressure sensing unit 215 is as follows.

The pressure sensing unit 215 includes a vertical pressure sensing unit 216 and a pen pressure sensing unit 217 .

When the tip 210 contacts the touch screen TSP, the vertical pressure sensing unit 216 senses the pressure F1 applied perpendicularly to the length direction of the tip 210 . When the pressure F1 in the vertical direction is applied to the tip 210, the tip 210 is bent, and the vertical pressure sensing unit 216 measures the pressure F1' in the vertical direction applied when the tip 210 is bent. Detect and acquire vertical pressure information. The pen pressure sensing unit 217 acquires pen pressure information by sensing the pressure F2 applied in the longitudinal direction of the tip 210 .

The receiving unit 230 of the active touch pen 20 includes a receiving buffer 231 , an amplifier 233 , and a comparator 235 . The reception buffer 231 receives the touch screen driving signal Ts transmitted through the switching unit 220 and applies it to the amplifier 233 . The amplifier 233 is configured in at least two stages to amplify the analog level touch screen driving signal Ts to increase the sensitivity of the received signal. The comparator 235 compares the signal amplified by the amplifier 233 with an internal reference voltage, and generates a comparator output signal COM of a digital level with respect to the reference voltage or more or less than the reference voltage. Here, the comparator 235 uses a signal equal to or higher than the reference voltage as the comparator output signal COM when the amplifier 233 is implemented as an inverting amplifier, and is less than or equal to the reference voltage when the amplifier 233 is implemented as a non-inverting amplifier. can be used as the comparator output signal (COM).

As described above, the signal processing unit 250 of the active touch pen 20 determines the timing synchronized with the touch screen drive signal Ts based on the comparator output signal COM, and then generates the pen drive signal according to the synchronization timing. create In addition, the signal processing unit 250 modulates the pen driving signal based on the pressure information input from the pressure sensing unit 215 and outputs the pen driving signal Ps to which the pressure information is reflected.

The pressure information included in the pen driving signal Ps includes vertical pressure information and pen pressure information. The vertical pressure information is used by the touch driving device to calculate touch correction coordinates. A method for the touch driving device to calculate touch correction coordinates using vertical pressure information will be described later.

The touch pen 20 transmits the pressure information in a manner that adjusts the amplitude and/or the number of pulses of the modulated pen driving signal Ps according to the signal level of the pen pressure information. The driving unit 240 of the active touch pen 20 is a level shifter ( 243 ) and the transmission buffer 241 , the modulated pen driving signal Ps input from the signal processing unit 250 is converted into an analog level and output to the switching unit 220 . Then, the switching unit 220 transmits the modulated pen driving signal Ps to the tip 210 .

13 is a diagram illustrating a touch screen driving signal and a pen driving signal within a touch sensor driving period.

Following the on operation of the active touch pen 20 , after the active touch pen 20 comes into contact with the touch screen TSP, the reception period Ra of the touch screen driving signal Ts and the modulated pen driving signal Ps A signal conversion period of at least one frame or more is provided between the transmission periods Ta to ensure operation stability. The signal processing unit 250 generates a modulated pen driving signal Ps by determining a synchronization timing using this signal conversion section and reflecting the pressure information accordingly.

In the subsequent frame, the process (Ta) of transmitting the modulated pen driving signal (Ps) synchronized with the touch screen driving signal (Ts) to the touch screen (TSP) through the tip (210), and the touch through the tip (210) A process Ra of receiving the screen driving signal Ts is repeatedly performed alternately.

The driving signal Ps of the touch pen 20 includes a sensing signal output period (period1) and an additional information output period (period2). The sensing signal output period (period1) is a period in which a sensing signal for recognizing touch coordinates is output, and the additional information output period (period2) is a period in which additional information such as vertical pressure information and pen pressure information is output.

14 is a flowchart illustrating a method in which the touch driving device compensates for touch coordinates based on vertical pressure information obtained by the touch pen. A touch correction algorithm to be described later may be performed by the touch correction unit 180 illustrated in FIGS. 2 to 7 .

Referring to FIG. 14 , when the pen driving signal Ps is transmitted, the touch input calculator 1811 of the touch driving device 180 calculates pen touch coordinates and palm peak coordinates. The pen touch coordinates are coordinates of a point at which the driving signal Ps of the touch pen 20 is transmitted, and the palm peak coordinates are one of coordinates where the user's hand touches the touch screen TSP.

As shown in FIG. 15 , in the process of bringing the touch pen 20 into contact with the touch screen TSP, it is common for the user's hand to also contact the touch screen TSP. Accordingly, when using the touch pen 20 , the touch input calculator 181 obtains a plurality of touch coordinates. The touch input calculator 181 of the touch driving device 18 divides the plurality of touch coordinates into pen touch coordinates P1 and palm coordinates P2-1 to P2-11 as shown in FIG. 16 . The criterion for classifying the pen touch coordinates P1 and the palm coordinates P2-1 to P2-11 may be determined based on the number of labeled touch coordinates by labeling the touch coordinates. In the touch screen TSP, the number of touch sensors whose capacitance is changed by the touch pen 20 is one or several, whereas the number of touch sensors whose capacitance is changed by the user's hand is very large. Accordingly, the touch compensator 180 sets the small number of labeled touch coordinates as the pen touch coordinates P1, and sets the touch coordinates including the relatively large number of labeled touch coordinates as the palm coordinates P2-1 and P2-11. set to

The touch input calculator 181 sets palm peak coordinates (x', y') among the palm coordinates (P2-1, P2-11). When the touch pen 20 is projected on the touch screen TSP in the vertical direction, the touch input calculator 181 calculates a point in the region where the touch pen 20 is located as the palm peak coordinate P2 . .(S103)

The horizontal angle calculator 183 calculates the direction of the palm peak coordinates P2 from the pen touch coordinates P1 as a tip horizontal vector V_T. In addition, the horizontal angle calculator O calculates a trigonometric function with respect to the horizontal angle θ formed between the reference axis and the tip horizontal vector V_T. The reference axis L may use either the x-axis or the y-axis in the touch coordinate system. 17 shows an example in which the x-axis passing through the pen touch coordinates P2 is set as the reference axis L. As shown in FIG.

In order to calculate the trigonometric function for the horizontal angle θ, the horizontal angle calculator 183 uses the distance c from the pen touch coordinates P1 to the palm peak coordinates P2 as a hypotenuse, and the pen touch coordinates P1. and the absolute value of the y-coordinate component difference of the palm peak coordinates (P2) is the height (a), and the absolute value of the x-coordinate component difference between the pen touch coordinates (P1) and the palm peak coordinates (P3) is the base (b). Set up a right-angled triangle.

The horizontal angle calculator 183 calculates cosθ and sinθ with respect to the horizontal angle θ. The horizontal angle calculator 183 calculates cosθ by calculating b/c for . The horizontal angle calculating unit 183 calculates sinθ by calculating a/c for . In this case, the hypotenuse c may be calculated using the Pythagorean theorem. (S105)

The error length calculator 185 calculates an error length based on vertical pressure information included in the additional information output period period 2 in the pen driving signal Ps. The error length ℓ refers to the degree to which the actual touch input coordinates are distorted according to the degree to which the tip 210 is inclined in the vertical direction of the touch screen TSP, as shown in FIG. 9 . 9, since the distance between the tip 210 and the touch screen TSP is narrowed in the direction in which the tip 210 is inclined, the tip 210 and the tip 210 and A change in capacitance occurs between the touch screens TSP. As a result, the area in which the tip 210 is in contact with the touch screen TSP is the 'P3' point, but the touch input calculator 181 selects the 'P1' point where the tip 210 is inclined in the inclination direction of the touch input coordinates. is calculated as The degree to which the touch input coordinates P1 are deflected from the contact coordinates P3 is proportional to the tilt degree of the tip 210 . And the magnitude of the vertical pressure F1 applied in the vertical direction of the tip 210 also increases according to the degree of inclination of the tip 210 . Conversely, the error length calculator 185 may calculate an error length ℓ representing a deviation from the touch coordinate P3 to the touch input coordinate P1 based on the vertical pressure information in the touch driving signal Ts. have. The error length (ℓ) may be stored in a preset look-up table by matching one-to-one with the vertical pressure information, and the error length calculator 185 may extract an error length that matches the vertical pressure information from the look-up table. ( S105)

The touch input corrector 187 compensates the touch coordinates in the negative vector direction opposite to the tip horizontal vector V_T in the pen touch coordinates. The touch input correction unit 187 sets the error length to the size of the compensation value. That is, the touch input corrector 187 may calculate the touch coordinate P3 by using the horizontal angle θ and the error length ℓ in the touch input coordinate P1 .

The x-axis coordinate (x") of the contact coordinate P3 is calculated as in [Equation 1] below.

[Equation 1]

x"= x + error length (ℓ)*cosθ

The y-axis coordinate (y") of the contact coordinate P3 is calculated as in [Equation 2] below.

[Equation 2]

y"= x + error length (ℓ)*sinθ

As described above, according to the present invention, it is possible to correct the deflection of the touch input coordinates due to the inclination of the touch pen 20 . Accordingly, since the point at which the user makes contact with the touch pen 20 can be more accurately obtained, touch accuracy can be improved, and as a result, the usability of the touch screen can be increased through precise touch input.

Those skilled in the art from the above description will be able to see that various changes and modifications are possible without departing from the technical spirit of the present invention. Accordingly, the technical scope of the present invention should not be limited to the contents described in the detailed description of the specification, but should be defined by the claims.

10: display device 18: touch drive device
20: touch pen 215: pressure sensing unit
216: vertical pressure sensing unit 217: pen pressure sensing unit
210: tip 220: switching unit
230: receiving unit 231: receiving buffer
233: amplifier 235: comparator
240: drive unit 241: transmit buffer
243: level shifter 250: signal processing unit

Claims (13)

An active touch pen that outputs a pen driving signal through a tip so that a touch driving device that detects a change in capacitance of a touch screen and calculates touch coordinates corrects the touch coordinates according to a tip angle,
When the tip contacts the touch screen, it receives a touch driving signal from the touch screen in a receiving section, and drives the first and second pens synchronized with the touch driving signal in a transmission section temporally separated from the receiving section a tip for transmitting the pen driving signal including a signal to the touch screen;
Using a plurality of pressure sensors disposed to surround the periphery of the distal region of the tip, the tip is applied to the tip in a vertical direction perpendicular to the longitudinal direction of the tip according to the inclination of the tip in contact with the touch screen. a vertical pressure sensing unit that senses the falling vertical pressure;
a pen pressure sensing unit sensing pen pressure applied to the tip in a longitudinal direction of the tip in contact with the touch screen; and
The first pen driving signal is synchronized with the touch driving signal received through the tip, and at least one of an amplitude and a number of pulses is adjusted according to the level of the pen pressure information detected by the pen pressure sensing unit to generate the first pen driving signal during the transmission period. a signal processing unit for outputting to the tip during one output period, generating a second pen driving signal including vertical pressure information detected by the vertical pressure sensing unit, and outputting the second pen driving signal to the tip during a second output period of the transmission period; active touch pen. delete delete touch screen;
a touch driving device for applying a touch driving signal to the touch screen and sensing a change in capacitance of the touch screen to calculate a plurality of touch input coordinates; and
When the tip contacts the touch screen, the touch driving signal is received from the touch screen in the receiving section through the tip, and the first and an active touch pen transmitting a second pen driving signal to the touch screen through the tip;
The active touch pen,
The tip is applied to the tip in a vertical direction perpendicular to the length direction of the tip according to the inclination of the tip in contact with the touch screen using a plurality of pressure sensors disposed to surround the periphery of the tip region of the tip. The vertical pressure information is detected by sensing the vertical pressure, the pen pressure information is detected by detecting the pen pressure applied to the tip in the longitudinal direction of the tip in contact with the touch screen by using the pen pressure sensor, and the level of the detected pen pressure information generates the first pen driving signal whose amplitude and the number of pulses is adjusted according to A signal is generated and transmitted through the tip during a second output period of the transmission section,
The touch drive device,
a touch input calculator configured to calculate pen touch coordinates and palm peak coordinates according to the number of labels in the plurality of touch input coordinates;
a horizontal angle calculator configured to calculate the palm peak coordinate direction from the pen touch coordinates as a tip horizontal vector, and to calculate horizontal angle information between a reference axis and the tip horizontal vector in the touch coordinate system;
an error length calculator configured to calculate an error length of the pen touch coordinates based on the vertical pressure information; and
and a touch input correction unit calculating touch correction coordinates obtained by compensating for the error length in a negative vector direction opposite to the tip horizontal vector from the pen touch coordinates. 5. The method of claim 4,
The touch input calculation unit
Set touch input coordinates with a large number of labeled among the plurality of touch input coordinates as palm coordinates;
A touch sensing system for setting arbitrarily selected coordinates among the palm coordinates as palm peak coordinates. 5. The method of claim 4,
The horizontal angle calculation unit
an absolute value a of the difference between the pen touch coordinates and the y-coordinate component of the palm peak coordinates;
Absolute value b of the difference between the pen touch coordinates and the x-coordinate component of the palm peak coordinates;
calculating the distance c between the pen touch coordinates and the palm peak coordinates,
A touch sensing system for calculating a trigonometric function for the horizontal angle according to the proportions of a, b, and c. 5. The method of claim 4,
The error length calculation unit
A touch sensing system for calculating the error length to be proportional to the vertical pressure. 7. The method of claim 6,
The touch input correction unit
correcting the x-coordinate of the pen touch coordinates by multiplying the touch compensation length by b/c,
A touch sensing system for calculating the touch compensation coordinates by multiplying the touch compensation length by a/c to correct the y coordinates of the pen touch coordinates. When the tip of the active touch pen contacts the touch screen, a first touch driving signal is received from the touch screen in a receiving section through the tip, and synchronized with the touch driving signal in a transmitting section temporally separated from the receiving section and a plurality of pressure sensors disposed to surround a periphery of an end region of the tip so as to transmit a second pen driving signal to the touch screen through the tip according to the inclination of the tip in contact with the touch screen. The vertical pressure information is detected by sensing the vertical pressure applied to the tip in the vertical direction of the tip perpendicular to the longitudinal direction of the tip, and the tip is placed in the longitudinal direction of the tip in contact with the touch screen using a pen pressure sensor. The pen pressure information is detected by sensing the pen pressure applied, and the first pen driving signal having at least one of an amplitude and a number of pulses adjusted according to the level of the detected pen pressure information is generated to generate the first pen driving signal in the first output period during the transmission period. outputting to the tip, generating the second pen driving signal including the detected vertical pressure information and outputting the second pen driving signal to the tip during a second output period of the transmission section;
calculating pen touch coordinates and palm peak coordinates according to the number of labels in the plurality of touch input coordinates;
calculating the palm peak coordinate direction in the pen touch coordinates as a tip horizontal vector, and calculating horizontal angle information between the reference axis and the tip horizontal vector in the touch coordinate system;
calculating an error length of the pen touch coordinates based on the vertical pressure information; and
and correcting a touch input by compensating for the error length in a negative vector direction opposite to the tip horizontal vector in the pen touch coordinates. 10. The method of claim 9,
The step of calculating the touch input is
setting touch input coordinates with a large number of labeled coordinates among a plurality of touch input coordinates as palm coordinates; and
and setting arbitrarily selected coordinates among the palm coordinates as palm peak coordinates. 10. The method of claim 9,
The step of calculating the horizontal angle information
calculating an absolute value a of a difference between the pen touch coordinates and the y-coordinate component of the palm peak coordinates;
calculating an absolute value b of a difference between the pen touch coordinates and the x-coordinate component of the palm peak coordinates;
calculating a distance c between the pen touch coordinates and the palm peak coordinates; and
and calculating a trigonometric function for the horizontal angle according to the proportions of a, b, and c. 10. The method of claim 9,
The calculating of the error length includes calculating the error length in proportion to the vertical pressure. 13. The method of claim 12,
The step of correcting the touch input is
correcting the x-coordinate of the pen touch coordinates by multiplying the touch compensation length by b/c; and
and correcting the y-coordinate of the pen touch coordinates by multiplying the touch compensation length by a/c.

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